Hot Surface Igniter / Flame Sensor / Control Timing - A.O. Smith Cyclone Xi Service Handbook

HOT SURFACE IGNITER / FLAME SENSOR / CONTROL TIMING

HOT SURFACE IGNITER
This water is equipped with an electric hot
surface igniter. The igniter material is
silicone carbide and should not be handled
with bare hands because of possible damage
to the igniter.
The normal ohm reading at 77° F is listed
between 40 and 70 ohms. The minimum
igniter current monitored by the CCB is 2.7
amps. Once this threshold is met a check
mark will appear by the igniter icon in the
UIM (display).
FLAME SENSOR
This water heater is equipped with an
electronic flame sensor. The flame sensor
senses flame by passing a small electric
current through the burner flame. This type
of flame sensing is also known as flame
rectification. The CCB is looking for a
minimum current of .7 micro amperes for the
water heater to operate. Once this current is
established the UIM will display a flame icon.
A.O. Smith – Technical Training Department
CYCLONE Xi COMMERCIAL GAS WATER HEATER
BTH 120 thru 500 SERVICE HANDBOOK
Servicing should only be performed by a Qualified Service Agent
CONTROL TIMING
Pre-purge
Igniter Warm-up
Trial for ignition
Gas Control Open
Inter/Post Purge
36
25 seconds
17 seconds
5 seconds
30 seconds
Ashland City, Tennessee © 2009
316586-000